1. Field of the Invention
The present invention relates to a multiplexed audio data decoding apparatus for decoding voice/audio signals which are encoded with compression format, and in particular, to a multiplexed audio data decoding apparatus and a receiver apparatus which can be used preferably as a receiver for digitized broadcasting, in which many channels are multiplexed.
2. Description of Prior Art
As a method being applied to, in general, for compressing digital audio signals, there are known MPEG (Moving Picture Experts Group) Audio and a method so-called by “AC-3” which is applied to by ATSC (United States Advanced Television System Committee). Both of those methods are based upon a technology, in which information on a time axis is converted into data on a frequency axis, and is compressed by dividing it into frequency bands with using a psychological auditory characteristic, such as masking effects, or by using correlation between audio channels.
A method for decoding audio bit streams which are compressed by using those methods, being based on DSP (Digital Signal Processor), is described in “Design And Implementation of AC-3 Codes, Vol. 41 No. 3, August 1995”, as an audio decoder corresponding to the AC-3 format. The DSP, in the same manner as a general micro-controller, takes a method of processing data by interpreting the software program codes in a built-in register(s) so as to store them into a memory(s). Therefore, as compared to the method for realizing or achieving it by means of hardware, it is possible for it to have decoding algorithms in plural formats as decoding process codes for each, and also it has a flexibility with the changes thereof, thereby being considered to be advantageous in both view points of costs and handling property thereof. Further, it is characterized by the fact that the calculation speed thereof is improved, by devising or providing a means of hardware for exclusive use, such as a high speed multiplier, or by smoothing the data flow therein with provision of a plurality number of data buses.